Support multiple arguments with C version

Accept more than one argument and print their IP addresses in order:
```shell
➜  gfw_dns_resolver git:(support-mult-argv) ✗ ./a.out soso.com baidu.com twitter.com
The real ip is: 111.13.96.137
The real ip is: 220.181.111.85
The real ip is: 199.59.148.10
```